1. Field of the Invention
This invention relates to a electromagnetically operable display elements, and to a novel mans of operating and mounting them.
2. Brief Discussion of the Related Art
Such display elements are exemplified by: anyone of those shown in:
U.S. Pat. No. 5,050,325 Browne
U.S. Pat. No. RE 35,357 Browne
U.S. Pat. No. 5,337,077 Browne
U.S. Pat. No. 4,566,210 Winrow
U.S. Pat. No. 5,156,872 Helwig
whose contents are incorporated herein by reference. The devices in such patents are examples of such elements, wherein an electromagnetic core is switched in magnetic polarity by a coil surrounding the core. The display element switches between OFF to ON state responsive to a change in core polarity. In OFF state a rotor or other moving element displays one appearance (usually dark) in the viewing direction, and a contrasting appearance is displayed, which is usually bright, in ON state. For example:
______________________________________ Viewing Direction Viewing Direction Patent Appearance in ON State Appearance in OFF State ______________________________________ 5,050,325 Bright Disk Side Dark Disk Side with LED LED shuttered RE 35,357 Bright Disk Side Dark Disk Side with Fibre Optic Optic is shuttered 5,337,077 Fibre Optic Optic is shuttered 4,566,210 Bright side of Bright side is Lever hidden 5,156,872 One side of Disk Contrasting side of Disk ______________________________________
In each of the above examples the cores are wound with helical coils to provide the magnetizing turns. A separate means is provided for mounting the display elements whether as single indicators, rectangular modules or large arrays or other arrangements. The mounting means involves considerable expense.
In accord with this invention an insulating board is provided with conducting paths formed on a surface thereof which paths act as a turn or a series of turns about a core. The final insulating board may be a lamination of a number of sub layers of such boards if the number of turns requires more turns than can be conveniently placed on one surface. The conductors are arranged relative to an aperture for a core. The `flat coil`, so called to differentiate it from the usual helical coils, may be prefabricated on a surface of the insulating board or its layers. Hence the step of winding is eliminated. A flat coil of more than one turn will include a spiral which need not be geometrically regular. The number of turns on any one surface is limited by the fact that there is a limit for spiral size set when the outer turns do not have a successful magnetization effect.
Moreover the cost of a module or array is reduced since the board may be prefabricated with an array of core apertures which may be used to mount the cores and achieve the arrangement of the display elements in a module or array. The display element comprising the stator and rotor may be mounted on the board. The cost of a former mountings for element, module or array as encountered in the prior art is eliminated. By "board" herein is meant a relatively flat board of (preferably) dielectric material commonly used to mount circuits, or circuit components, and is here used to receive the flat coils. Preferably, the board is of the same material as those commonly used for printed circuit boards or printed wiring boards and is commonly made of fiberglass-filled epoxy resin, although boards formed from other materials may be used. The board as described herein is used to mount the flat coils and the display elements in desired relationship to the coils and to each other. `Board` herein includes a lamination of sub layers of thinner boards.
By `flat coil` herein, I mean a pattern of thin ribbon or film conductors formed on the surface of a board layer or on sub-layers thereof to magnetize a core passing through the board within the magnetic field of the coil. Thus, the magnetization will be in opposite senses for opposite current flow through the coil. A `flat coil` includes a series of coils surrounding a common bore but arranged on different sub layers of the board.
Commonly the pattern of film or ribbon is formed on the board by covering it with attached metal foil and etching away the portion not desired for the pattern. The foil is usually of copper. The invention is not however dependent on the method of forming the laminated conductor on the board. Thus, this conducting patterns may be supplied by painting, printing or deposit where commercially practical methods are available. A conductor or copper or other metal may be provided with a surface of tin or precious metals for better electrical contact.
A `pin` is that part of a core which magnetically drives or retains the moving member of a display element. The first three patents listed on page 1 show display elements using two pins on the core while the latter two elements show display elements with a single pin on the core. The pins may also act as stops for the movable member in some display elements.